The present invention relates to a hydraulic locking device whereby a rod is locked by a sleeve having elastic deformations which are elastically deformed by hydraulic pressure. More specifically, the present invention relates to a hydraulic locking device constructed so that the sleeve is elastically deformed by generating a high hydraulic pressure using a hydraulic intensifier provided inside a case member.
A conventional hydraulic locking device is used for clamping and supporting a workpiece locking it into a desired position for cutting, or the like, of the workpiece. For example, Japanese Utility Model Laid-open Patent Publication 59-128902 and Japanese Utility Model Laid-open Patent Publication 6-47710 describe this type of hydraulic locking device.
In Japanese Utility Model Laid-open Patent Publication 59-128902, a hydraulic locking device has an approximately cylindrical case member. A hollow piston member slidably fits inside the case member. The hollow piston member can be elastically deformed to have a smaller diameter. A rod, slidably fitting inside the hollow piston member, passes through the case member. According to this hydraulic locking device, by introducing oil into the hydraulic pressure chamber that is between the case member and the piston member, there is elastic deformation of the piston member, pressing the piston member into contact with the rod. The piston member and the rod are locked so that there is no relative displacement in the axial direction.
In Japanese Utility Model Laid-open Patent Publication 6-47710, a hydraulic locking device has a hydraulic cylinder equipped with a cylinder body and a piston member that slidably fits inside the cylinder body. A rod, passing through the cylinder body, has a piston member passing through it in the axial direction. An elastically deforming sleeve, between the piston member and the rod, fits outside the rod and is attached to the piston member, preventing relative displacement in the axial direction. According to this conventional hydraulic locking device, hydraulic pressure introduced to the hydraulic pressure chamber formed inside the piston member is transferred on the outer periphery of the sleeve, elastically deforming the sleeve. Thereupon, this sleeve is pressed into contact with the outer perimeter surface of the rod. The rod is locked to the piston member to prevent relative displacement.
In the hydraulic locking devices described in Japanese Utility Model Laid-open Patent Publication 59-128902 and Japanese Utility Model Laid-open Patent Publication 6-47710, the sleeve, which is either integral with the piston member or is separate from the piston member, is elastically deformed to have a smaller diameter due to the hydraulic pressure. The rod is locked by the static frictional force acting between the sleeve and the rod. With this construction, if the hydraulic pressure to elastically deform the sleeve is a low pressure, the locking force is small. In order to generate a large locking force, a large locking device is necessary. This is disadvantageous in terms of equipment costs. Otherwise, a high-pressure hydraulic pressure must be supplied from the hydraulic pressure supply source. This causes the hydraulic pressure supply source to become large, and also results in hydraulic pressure leaks being more easily generated. This results in a bulky and expensive hydraulic locking device.
It is an object of the present invention to provide a hydraulic locking device which overcomes the foregoing problems.
More specifically, it is an object of the present invention to devise a smaller, high powered hydraulic locking device.
It is another object of the present invention to devise a smaller and a lower pressure hydraulic pressure supply source.
Briefly stated, the present invention provides a hydraulic intensifier which generates a hydraulic pressure that is higher than the input hydraulic pressure generated in the discharge port and the outer periphery hydraulic pressure chamber. The hydraulic intensifier, provided inside a case member, has a discharge part connected with an outer periphery hydraulic pressure chamber. An input port supplies input hydraulic pressure from the exterior to an input oil chamber of hydraulic intensifier. Oil is filled in a sealed manner in outer periphery hydraulic pressure chamber and discharge part. The hydraulic intensifier is driven by the input hydraulic pressure. The rod is locked by the elastic deformation of a thinned tube part of a sleeve body. A relatively small hydraulic locking device having a relatively high power is achieved. Furthermore, a relatively small hydraulic pressure source having reduced pressure is realized.
The present invention is a hydraulic locking device having a rod as an output member. A sleeve body, fitting outside the rod, is equipped with a thinned tube part that can be elastically deformed to a smaller diameter. A case member supports the sleeve body. An outer periphery hydraulic pressure chamber is formed on the outer periphery side of the thinned tube part of the sleeve body. A hydraulic intensifier, provided inside the case member, has a discharge part continuous with the outer periphery hydraulic pressure chamber. An input port supplies input hydraulic pressure from the exterior to the input oil chamber of the hydraulic intensifier. Oil that is filled, in a sealed manner, in the outer periphery hydraulic pressure chamber and discharge part. The hydraulic intensifier is driven by the input hydraulic pressure supplied from the input port. Hydraulic pressure, having a higher pressure than the input hydraulic pressure, is generated in the discharge part and outer periphery hydraulic pressure chamber. Locking of the rod being is conducted by elastically deforming the thinned tube part of the sleeve body to a smaller diameter.
An example wherein the workpiece being supplied for machining is supported from underneath by the hydraulic locking device will be described. The workpiece is supplied from above the hydraulic locking device. While the rod is in contact with this workpiece, the rod is pushed downward. When the workpiece reaches the desired height, input hydraulic pressure is supplied from the input port to the input oil chamber of the hydraulic intensifier. Thereupon, driving the hydraulic intensifier results in a hydraulic pressure that is higher than the input hydraulic pressure is generated in the outer periphery hydraulic pressure chamber on the outer periphery of the sleeve and in the discharge part. Next, the thinned tube part of the sleeve body is elastically deformed to a smaller diameter, securely locking the rod. In particular, because the hydraulic intensifier is driven by a low input hydraulic pressure and the oil, which is filled in a sealed manner in the outer periphery hydraulic pressure chamber and the discharge part, is intensified to a higher pressure than the input hydraulic pressure, a high powered locking device can be devised without requiring a large locking device. The hydraulic pressure supply source is thus made smaller and has a reduced pressure.
The hydraulic intensifier has an annular piston member that fits outside the sleeve body. The discharge part of the hydraulic intensifier is preferably formed on the outside periphery of the thinned tube part of the sleeve body. The hydraulic intensifier can be provided inside the case member without having to increase the diameter of the case member. The space on the outer periphery of the sleeve body is thus effectively used.
A spring housing hole, open on one end, is formed near the shaft core of the rod. A spring bearing member is inserted partially in this spring housing hole in a manner allowing for relative displacement. The spring bearing is affixed to the bottom wall of the case member. A compression spring is attached to the spring housing hole and is stopped by the spring bearing member is provided. The rod is preferably elastically impelled towards the other end by the compression spring. The rod is constantly elastically impelled towards the other end by the elastic impelling force of the compression spring.
A spring housing hole, open on one end, is formed near the shaft core of the rod. A spring is housed in the spring housing hole, and a spring bearing piston member receives one end of the spring. It is preferable to have a hydraulic pressure chamber that has hydraulic pressure acting on the spring bearing-piston member, receiving an external supply of hydraulic pressure. When a low input hydraulic pressure is supplied to the hydraulic pressure chamber from the input port, the spring bearing piston member slides to the other end in opposition of the impelling force of the spring, compressing the spring. Thereupon, the rod is shifted to the other end and contacts the workpiece that is provided on top of this device. Next, driving the hydraulic intensifier, and a hydraulic pressure, of higher pressure than the input pressure, is generated in the outer periphery hydraulic pressure chamber and discharge part. By this, the thinned tube part of the sleeve body is elastically deformed to a smaller diameter, securely locking the rod.
The above hydraulic intensifier preferably has a piston member housing hole formed inside the inner wall of the case member at a position separated from the sleeve body. The hydraulic intensifier preferably also has a piston member that is housed shiftably in the piston member housing hole and that has a pressure receiving part and a pressure applying part. The workpiece is in contact with the rod and is pushed. At the desired height of the workpiece, a low-pressure input hydraulic pressure from the input port is received by the pressure receiving part of the piston member. Thereupon, the piston member slides inside the piston member housing hole. The oil in the discharge part is pressurized by the pressure applying part. A hydraulic pressure of higher pressure than the input hydraulic pressure is generated in the outer periphery hydraulic pressure chamber and the discharge part. By this, the thinned tube part of the sleeve body is elastically deformed to a smaller diameter, and securely locking the rod.
The above rod is preferably provided so that it protrudes to the exterior from one end of the case member. With this hydraulic locking device, the workpiece used in machining is pressed into contact with the rod and is pushed. At the desired position, the rod is locked, and the workpiece can be securely supported by clamping and the like.
The above rod is preferably provided so that it passes through the sleeve body and case member. As a result, after adjusting the rod which passes through the sleeve body and case member to the desired position, the input hydraulic pressure is supplied and the rod can be locked.